Just made my annual trip to the Glen for 3 days with the Ferrari boys, but had to head home after 1 day as I broke a stud in the right rear wheel. Not sure what it is about the Glen, but last year was also impacted with 2 cracked rear wheels.


Anyways, the threaded part is still in the hub so will require some heat to extract given the liberal use of red loctite. Some (poor qualityy) pics below.
The studs have probably 30 days of use, and after speaking with a couple of race shops, it sounds like they should be lasting longer. It was clear that the stud in question, had been cracked previously as a good part of the cross section was corroded. Coincidentally, I have already bought a new set of studs (Apex Comp race studs - same as current set).

Before I commit to installing these again, just want to make sure there isn't a better option or some precautions I shoud be taking. And for those that use studs, how frequent do you change them, and is breakage a common occurence.

Thanks.

 

Why didn't you just use an EZ out and remove the broken half?

Apex instructions suggest using a medium thread lock compound. Red is probably too much for this application given this exact same situation.

Maybe go with the bullet nose next time so you're banging on the studs as much with the wheel when mounting. I'm putting my bullet nose 80mm's in this week. Going to use blue loctite just so I can get them out again if need be. The pressure of just torquing the nuts should keep them pretty well seated.

 

Which studs were you using?

 

Looks like the 'Race' studs with the shoulder section (link)

 

Maybe a batch of bad metal? Trying to figure out what causes a stud to snap like that assuming no drover error (i.e., improper torque, loose, etc.).

Anybody with a metallurgy background?

 

I use studs on my hubs e.g.. The kind that stick OUT.. The OEM stubs are hard on the threads of the hub and not intended for repeated application and torquing. I change them out every year or two..

 

Them's the ones. Can say that I'm **** when it comes to torquing so they're checked at least once and usually twice a day. Also have my torque wrench calibrated annually so I'm pretty confident that I've not over torqued them. Also no driver induced event - other than hard track driving - that would cause them to be over stressed.

Having said that, the tech inspection at the Ferrari event was a bit of a gong show, and I had to leave my keys with the tech guy while I attended the drivers meeting. When I came out of the meeting, my car was teched incl torque check every wheel bolt/lug nut. Now wondering if they were maybe over torqued during the tech. Either way though, the cross section suggests some prior corrosion so the problem started previously, which makes me call in to question all of the studs. Curious if anyone else has had the same issue with the Apex comp race studs.

 

Doubtful you'll ever get a root cause. Ping Bill @ Apex and get his 0.02. I wouldn't replace all of them though due to this failure; maybe a thorough inspection with a bright flash light and maybe a magnifying glass. Otherwise, IMO replace the broken one and move on.

 

I had couple studs break on 1 wheel recently. It happens. They fatigue and a little crack will oxidize and eventually turn into a big one. Eventually it will fail. A little heat and an eazy out works wonders, even with red loctite. Because a couple broke, I'm replacing all of them just to be safe. Pretty cheap insurance.

Just thank your lucky stars that losing one didn't start a domino effect with all of them snapping off.

-td

 

How much torque did you apply to the studs when you initially installed them?

 

The torque when installing is minimal, especially compared to the nut torque securing the wheel.

 

My feelings exactly. If one had fatigued, who's to say that another one is not in the same state, and if it's on the same left rear wheel, then the remaining 4 have been over stressed and that could just accelerate the inevitable. Not a risk I want to take. BTW, what wheel did you have your 2 broken studs on ?

 

+1

 

Replace all on that hub, or all 20? I misread; I thought you meant all 20. All on the hub I can see as reasonable.

 

Replace all of them and send the broken one for analysis.
The cost vs safety for you and the other drivers = Great value for money.